"What are you waiting for? What more evidence do you need? If you think it's not going to happen to you, there are proof points all over the United States, all over the world," California Gov. Gavin Newsom said Wednesday.

Newsom was the first governor to issue a statewide stay-at-home order in March after health officials warned social distancing measures would be the most effective in curbing the spread of the virus.

Even if Americans follow mitigation measures closely, the US death toll could be at least 100,000, White House experts said this week. But without those measures in place, that number could be as high as 2.2 million, Dr. Deborah Birx, the White House coronavirus response coordinator, said.

It was these kinds of aggressive measures that helped some areas "flatten their curve," US Surgeon General Dr. Jerome Adams says.

"The good news is that states like Washington, like California, countries like Italy, when they leaned into aggressive mitigation, they're being able to flatten their curve," Adams told NBC.

"The governors get to make the decisions, but we're going to give them the best possible guidance we can and that's to stay at home and social distance," Adams said.

Since January 20 when the first US case was detected, more than 216,450Americans have been infected and 5,119 have died. At least 928 of those deaths were reported Wednesday -- the highest number reported in the country since the beginning of the outbreak.

Facing increasing pressure from local leaders and experts, governors in states including Florida, Georgia and Mississippi said they'd also be ordering residents to stay home.Georgia Gov. Brian Kemp also announced Wednesday students would not be returning to class this school year.

"I want to encourage my fellow Georgians to hang in there. I know you're tired of this but we must first overcome the obstacles in our path," Kemp said, according to CNN affiliate WSB.

President Donald Trump said Wednesday he would not issue a national stay-at-home order because different states have different infection rates.

"You have to look -- you have to give a little flexibility. If you have a state in the Midwest, or if Alaska for example doesn't have a problem, it's awfully tough to say close it down. We have to have a little bit of flexibility," he said.

The states without orders

The 11 states that have not issued statewide stay at home orders include: Alabama, Arkansas, Iowa, Missouri, North Dakota, Nebraska, South Carolina, South Dakota, Tennessee, Utah and Wyoming.

In Tennessee, Gov. Bill Lee issued a "Safer at Home" order Monday, directing all non-essential businesses to shut down through at least mid-April.

"I don't think we're going to have a strong, a large number of Tennesseans who are not going to comply with this order, and we will be monitoring that, and if we find something different than that, then certainly we'll make decisions around enforcement," the governor said, according to CNN affiliate WZTV.

Alabama, surrounded by states who just announced they'd be implementing stay-at-home orders, has not issued a similar order.

"Many factors surround a statewide shelter-in-place," Gov. Kay Ivey's office told CNN affiliate WSFA, "and Alabama is not at a place where we are ready to make this call."

One of the governor's concerns is the impact the order would have on businesses and residents whose "well-being also relies on being able to have a job and provide for themselves and their families," the affiliate reported.

Up to 16,000 New Yorkers could die

In hard-hit New York, Gov. Andrew Cuomo ordered all non-essential workers home last month.

On Wednesday, he cited a model that showed as many as 16,000 New Yorkers could die from the virus.

"If you believe these numbers, 16,000 deaths in New York, that means you're going to have tens of thousands of deaths outside of New York," the governor said. "So to the extent people watch their nightly news in Kansas and say well this is a New York problem, that's not what these numbers say."

"It says it's a New York problem today. Tomorrow it's a Kansas problem and a Texas problem and a New Mexico problem. That's why I say to my fellow governors and elected officials across this country, look at us today, see yourself tomorrow," he said.

New York, now the epicenter of the outbreak, has reported at least 84,025 cases and 2,219 deaths. At least 45,707 of those infections and 1,374 of the deaths are in New York City.

Emergency Medical Services (EMS) has received a record number of medical emergencies each day, with a 50% increase over normal daily call volume, the New York City Fire Department said in a news release.

Test that could identify those who had virus may be ready this month

Many hospitals have warned they're running out of space and supplies. In Georgia, Kemp said on the first day of April at least 3,520 medical surgery beds, 450 hospital beds and 1,006 ventilators were available. But he cited one study that showed the state could reach "peak hospital capacity" in about three weeks.

And healthcare experts also say staffing shortages as medical care workers test positive for the virus could slow the country's response to patients.

Dr. Birx said Wednesday a coronavirus antibody test could be available "within this month" -- which could help medical care workers identify who may have immunity to the virus.

"I've really called on every university and every state to develop ELISA's, you can buy the antigens and the controls online, and really work to test entire health care communities in your state and support them that way."

The ELISA, or enzyme-linked immunosorbent assay, test detects and measures antibodies in blood. If successful, the test could help identify those who have already had the virus, but have since recovered.

Experts have said that if a person has had the virus and developed antibodies, it will most likely mean they have built up immunity and the chances of that person being infected again drops dramatically.

That test could help identify medical workers who may have had the coronavirus and not known it, Birx said.

"I think really being able to tell them, the peace of mind that would come from knowing you already were infected, you have the antibody, you are safe from reinfection. 99.9% of the time, " she said.

A hot forecast continues Sunday for northwest Missouri and northeast Kansas with heat indicies anticipated to climb into the upper 90s - potentially 100s. Monday will also see temperatures in the low 90s.